Dual stepping angle stepper motor drive

Abstract

A stepping motor control circuit permitting selective operation of the motor in various modes such as half or full step mode. The circuit includes a pulse generator producing pulses at a selected motor step rate. A switch means selects the step size while a second switch selects the motor direction. An up/down counter counts pulses from the pulse generator in a direction correlated with the selected rotation direction. A read-only-memory is addressed as a function of the periodically repeating count in the up/down counter and the selected step size. The stored information at the addressed read-only-memory location actuates motor drive circuitry which generates energizing signals for the motor windings to drive the motor in the selected direction a distance corresponding to the selected step size at a step rate equal to the pulse rate of the pulse generator.

What is claimed is: 
     
       1. A stepping motor control circuit for selectively controlling the size of each step of a controlled stepping motor with a plurality of windings comprising, in combination: means selectively operable to produce step size indicating signals;   means to produce periodically repeating address signals where the signals change at the desired motor step rate;   read-only-memory means for storing predefined data which is changeable to suit the desired operation for the stepping motor at each of a plurality of addressable locations, said read-only-memory means being responsive to said step size indicating signals and said address signals to place the predefined data stored at the address defined by said step size indicating signals and said address signals onto the memory output terminals;   motor drive circuit means responsive to the predefined data at said memory output terminals to energize the motor windings specified by said data at said output terminals thus causing the motor to turn by a step whose size is indicated by the step size indicating signals.   
     
     
       2. The stepping motor control circuit of claim 1 additionally including a motor direction selector for controlling the direction said repeating address signals change so that said read-only-memory address either increases or decreases. 
     
     
       3. The stepping motor control circuit of claim 1 wherein said address signals producing means comprises a pulse generator and a pulse counter to count pulses produced thereby, the count in said counter produces said address signals. 
     
     
       4. The stepping motor control circuit of claim 2 wherein said address signals producing means comprises a pulse generator and a pulse counter responsive to said pulse generator and said motor direction selector, said pulse counter counts in a direction corresponding to the selected motor direction. 
     
     
       5. The stepping motor control circuit of claim 1 wherein said address signals producing means produces at least as many unique address signals as there are winding energizing combinations for stepping the motor by the step size indicated by said step size indicating signals. 
     
     
       6. The stepping motor circuit of claim 1 wherein said means to produce step size indicating signals is selectively operable to produce one of a plurality of selectable step size indicating signals. 
     
     
       7. A stepping motor control circuit for controlling the operation of a multi-winding stepping motor comprising, in combination: means to produce periodically repeating address signals where the signals change at the desired motor step rate;   read-only-memory means for storing predefined data which is changeable to suit the desired operation of the stepping motor at each of a plurality of addressable locations within said storage, said read-only-memory means being responsive to said address signals to place the predefined data stored at the location defined by said address signals onto the output terminals of said read-only-memory;   motor drive circuit means responsive to said predefined data on said output terminals to energize at least one motor winding in accordance with the predetermined data at said output terminals.   
     
     
       8. The stepping motor control circuit of claim 7 wherein said address signal producing means includes a counter operative to produce said address signals wherein said counter selectively changes either in an upward or a downward direction. 
     
     
       9. The stepping motor control circuit of claim 8 wherein said counter is a binary counter circuit with n bit positions where the count repeats every 2 n  changes of said counter. 
     
     
       10. A stepping motor control circuit for controlling a stepping motor with a plurality of windings comprising, in combination: a pulse generator to produce a string of pulses, each pulse for stepping the motor by one step;   a step size selector to produce a step size indicating signal to indicate the selected motor step size;   motor direction selector means;   a pulse counter responsive to said pulse generator and said motor direction selector for producing a periodically repeating pulse count which either steps in an increasing or decreasing direction depending on the selected motor direction for each pulse from said pulse generator;   read-only-memory addressable by said step size indication signal and said pulse count in said counter to access data which is changeable depending on the desired operation of the stepping motor from the address location, the data being indicative of the windings which are to be energized for each combination of said step size indicating signal and said repetitive pulse count;   means responsive to said access data to energize at least one said winding specified by said access data.   
     
     
       11. The stepping motor control circuit of claim 10 wherein said pulse generator is adjustable so as to produce pulses at a selectable pulse rate which corresponds to the motor step rate. 
     
     
       12. The stepping motor control circuit of claim 10 wherein said motor direction selector comprises a switch to provide one signal for one direction and another signal for the opposite direction. 
     
     
       13. The stepping motor control circuit of claim 10 wherein said step size selector comprises means to produce selectively at least two step size indication signals. 
     
     
       14. The stepping motor control circuit of claim 10 wherein said pulse counter is a binary pulse up/down counter with the count direction being controlled by said motor direction selector means. 
     
     
       15. The stepping motor control circuit of claim 10 wherein said read-only-memory contains preselected data so that each time a location is addressed, the data at the output terminals corresponds to the preselected data at the addressed location wherein each preselected data word identifies the motor windings which are to be energized to step the motor and move its rotor a distance corresponding to a step from the previous rotor position.